The image processing generally refers to digital image processing. A digital image is a two-dimensional array obtained after sampling or digitizing via equipment such as digital cameras, scanners etc., and an element in the array is called a pixel, and a array value thereof is an integer, which is known as a gray value. The image processing technology mainly comprises three parts: image compression, image enhancement and recovery, image matching and description, and image identification.
In existing image processing technologies, the method for processing image extension information mainly adopts Exif image file specification used by JPEG files, wherein, an Exif image file header is similar to a dictionary structure, and contains an index part and a content part. In general, the relatively important index information in tag type information (defined in the Exif standard) is put together as a first level dictionary. A second level dictionary and a supplementary dictionary are added at the end of the first level dictionary, wherein, the remaining index information is put into the supplementary dictionary. Each group of Exif tags has the same structure. The index information part is composed of characters with a specified length, and generally comprises the following contents: a tag type, such as a manufacture name and so on; a tag content type, such as ASCII and so on; a tag length, which is usually an integer; and an address where the tag content is located. Except for image compression data, all other extension information, such as photographic parameters of the equipment manufacture information, lenses, and apertures and so on, can be stored in corresponding tags.
Such method in the existing technologies can store the extension information of an image file; however there are also the following disadvantages: firstly, the problem of adding extension information for all image formats cannot be solved, and other image formats, such as BMP, GIF, WBMP and so on do not support the Exif format; secondly, users can implement extension information sections only if using a specialized imaging software which supports editing Exif information when needing to edit image extension information, and can only view the content of the extension information on the terminals supporting decoding the corresponding Exif extension information sections, thus being inconvenient to use; and thirdly, the method cannot support increasing the extension information sections by the users themselves, thus limiting the flexibility for the users to edit extension information.